Stability of cylindrospermopsin, the toxin from the cyanobacterium,Cylindrospermopsis raciborskii: Effect of pH, temperature, and sunlight on decomposition

Abstract

Cylindrospermopsin is a powerful hepatotoxin produced by the cyanobacterium Cylindrospermopsis raciborskii. It is considered a potential threat to livestock, wildlife, and humans, and is the suspected cause of an outbreak of hepatoenteritis on Palm Island, Queensland, Australia, and various stock poisoning incidents around Australia. In this study, the stability of cylindrospermopsin was investigated using different parameters, including visible and UV light, sunlight, temperature and pH. Cylindrospermopsin decomposes rapidly (half-life of 1.5 h) when exposed to sunlight in an algal extract solution; however, no decomposition was recorded in pure cylindrospermopsin and Milli-Q water solutions. Cylindrospermopsin decomposes slowly in temperatures ranging from 4 to 50°C at pH 7. After 10 weeks at 50°C, cylindrospermopsin had degraded to 57% of the original concentration. This degradation was accompanied by an increase in another compound which is believed to be structurally related to cylindrospermopsin. Boiling does not cause a significant degradation of cylindrospermopsin within 15 min. Initial investigations indicate that cylindrospermopsin is degraded slowly under artificial light ranging from 42, 29, and 9 μE m−1 s−1 and in darkness. Degradation of cylindrospermopsin was not affected by changes in pH. Experiments were performed in sterile conditions. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 155–161, 1999